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I'm an engineer with experience in applied cryptography, in particular in Smart Card systems.


Nov
26
revised Are there any digital signature algorithms in common use that result in 32-byte signatures?
Add missing term at verification step 6
Nov
26
revised Maximum length in bits of the product n=pq
Per request, explain how things are in practice.
Nov
26
revised Are there any digital signature algorithms in common use that result in 32-byte signatures?
Fix RSA public key fuction in verification
Nov
26
revised Are there any digital signature algorithms in common use that result in 32-byte signatures?
Give step-by-step description
Nov
26
revised Maximum length in bits of the product n=pq
Full proof
Nov
26
comment Maximum length in bits of the product n=pq
The assertion the total number of bits after multiplication will be 2*1024 is incorrect; counterexample: $p=q=2^{1023}+1155$.
Nov
26
answered Maximum length in bits of the product n=pq
Nov
26
revised simulating rc4-256 with rc4-128
point interesting comment
Nov
26
revised Are there any digital signature algorithms in common use that result in 32-byte signatures?
Give mitigation to attacks on ISO/IEC 9796-2 scheme 1 with SHA-1
Nov
26
revised Are there any digital signature algorithms in common use that result in 32-byte signatures?
Link to a description to the scheme, which is not so well known in theindustry; attempt to align notation to that source.
Nov
25
revised Are there any digital signature algorithms in common use that result in 32-byte signatures?
explain the risk
Nov
25
answered Are there any digital signature algorithms in common use that result in 32-byte signatures?
Nov
25
comment Small Encryption Exponent
@codeomnitrix: the assignment in this question was intended to be solvable in one iteration of the Fermat factoring method; that is, the simple 4 steps in this answer. That may be worth trying in your case (especially if there is any hint that the factors are very close, or mention of the method); and perhaps the full Fermat factoring.
Nov
25
revised simulating rc4-256 with rc4-128
added 4 characters in body
Nov
25
comment what are multi-primes and how are they different from semiprimes?
The patent, and more generally history of multi-prime RSA, are described in this question
Nov
25
answered simulating rc4-256 with rc4-128
Nov
24
comment Less known hash functions producing 128 bit hash
Have you tried RIPEMD and RIPEMD-128? They where not in the reference that you give as at the time you posted. Also, truncation of wider hashes are common. And a MAC with hard-coded key is common, and indistinguishable from a custom hash, even with a reverse-engineering of the code.
Nov
24
comment Building a pad for OTP on-the-fly with Diffie-Hellman
@Guut Boy: I was thinking of OTP with XOR, which is usually implied; and DH in $\mathbb Z_p^*$, again a default assumption. $\;$ I do agree that for $a$ random and chosen independently of $b$, and $g$ a generator of a suitable multiplicative group, $(g^a)^b$ is computationally indistinguishable from random.
Nov
24
awarded  Nice Answer
Nov
24
comment Building a pad for OTP on-the-fly with Diffie-Hellman
@Guut Boy: The question states "protocol would be as hard as breaking DH (discrete logarithm)", which is wrong even if we ignore the minor issue that breaking the DH problem might be easier than breaking the discrete logarithm problem. The issue is that reference to "discrete logarithm" makes it clear "DH" means the DH problem, not the DH protocol (because there is no discrete logarithm protocol). And the proposed protocol (as well as the DH protocol) is trivially broken by MiTM, when the DH problem is not.